The FDNY sent out a demand for payment addressed only to “unknown Asian” after EMS workers filled in sketchy patient information for a $784 ambulance ride.

The bill was sent to the vaguely described individual at The New School’s 2 W. 13th St. building, leaving staffers scratching their heads after the bill was delivered there Tuesday.

“I hesitated to open it but then I was like, ‘Well, I could be an unknown Asian,’” said Christine Ahn, 29, who works in the dean’s office at Parsons The New School for Design.

The FDNY — which charges people who require ambulance transport — addressed the mysterious bill to “UNKNOWN ASIAN, 2 W 13TH ST, NEW YORK NY 10011-7902.”

The bill bears the FDNY logo and demands $784.40 for a Nov. 1, 2013 emergency in which the patient was transported from 255 W. 14th St. — the address of an Associated Supermarket — to Beth Israel Medical Center on First Avenue.

“The funny thing for us was that there are so many Asians at this school,” said Ahn.

“We’ll just go down the hall and ask every Asian student if they needed medical assistance,” joked dean’s office assistant Chris Rivera, 34, who recounted the moment he found the bill in their office mail.

“When I saw it said ‘unknown Asian,’ I thought it was racist,” Rivera said. “I showed it to Christine and her supervisor — both of whom happen to be Asian — and Christine thought it was sort of disrespectful and rude.”

Both Rivera and Ahn want answers from the FDNY.

“There must be “unknown Hispanic” or “unknown African-American” bills out there,” Rivera said. “What else goes on in that agency?”

A FDNY source explained how the bill was generated.

When the female patient was transported at about 3 a.m. on Nov. 1 for a “drug or intoxication” issue, she could not be identified by name but a person accompanying them said the patient lived in a New School dorm so the EMS workers filled out the form with “unknown” for the first name and “Asian” for the last name, the source said.

The form was processed and sent to a fire department billing contractor, which then sent out the oddly-addressed bill.

“It’s a clerical or administration error that the bill was sent out,” the source said.

FDNY spokesman Jim Long said changes would be made to address the problem.

“We’re speaking to the vendor and we’re asking them not to process bills that have an unknown for the name,” Long told The Post.